Innovation in intermittent electricity and stationary energy storage in the United States and Canada: A review

Intermittent electricity generation and stationary grid storage are increasingly competitive with ongoing efforts to advance technologies towards market diffusion. We contribute an innovation systems perspective to understand better the co-evolution of early-stage public investments in research, development and demonstration, costs, and diffusion of technology and policy for intermittent renewables and storage in two federalist political systems (Canada and the United States). Our systematic review comparatively examines public investments in wind, solar, and storage technologies, as well as trends in costs, policy, and technology diffusion up to and including 2019. Our review contributes an account of the diffusion of renewable portfolio standards (RPS) as well as storage policies and targets at the subnational level in both countries. We quantify progress to policy goals, with findings pointing to substantial variability in the contribution of intermittent generation. Five states and one province surpassed goals with wind and solar power alone. One state and one province had less than 2% contribution from intermittent generation. While wind has a dominant force in meeting RPS goals in the United States, credit multipliers and carve-outs recently have resulted in high growth in solar power. Deployment of stationary storage is relatively nascent compared to wind and solar power, with increasing technology and policy diffusion very recently spurred by cost decreases in battery options. We identify data gaps that can be filled with more robust tracking of innovation metrics such as costs of storage technologies. Findings offer insight into how the interplay between costs, deployment, and policies can support improvements in energy technology innovation systems.